Interference fits of the pre-cited type between relatively thick-walled carriers and thin-walled bushing-type components made of sheet metal are used in machine construction and automotive vehicle construction, particularly in mechanical systems with complex design space conditions. Such bushing-type components make it possible to provide, at low costs, separating walls and mechanically high-grade surfaces particularly suitable for use as running surfaces.
Examples of use are bearing rings for needle roller bearings or cylindrical roller bearings that are drawn out of sheet metal and can be used without a finishing treatment of the rolling contact surfaces. Further examples are sealing surfaces that are formed by the surface of bushings after they have been drawn.
Through the interference connection between the carrier and the bushing, channels, for example, for medium guides can be formed by the fact that e.g., grooves in the surface of the carriers are covered with help of the thin-walled component, so that channels delimited on all sides get formed. Through such an arrangement, it becomes possible to dispense with high cost fabrication technology and the problematic mechanical structure configuration of long lubrication channels in solid material.
Bearing rings of radial rolling bearings and sealing bushings, as already mentioned, are bushing-type thin-walled components of sheet metal whose thin walls advantageously enable the radial design height to be kept at a low level. Such thin-walled components are made economically preferably by cold shaping, particularly by deep drawing out of sheet metal. As individual parts, thin-walled bearing rings are often comparatively non-circular in shape. They therefore have to be pressed into or onto the bearing seat of the carrier, so that they can assume the roundness required for rolling bearings. In addition, with the interference fit, the optimal radial bearing clearance and the firm seating of the respective bearing ring are achieved.
The respective cylindrical seating for the bearing ring or for the sealing bushing comprises, for reasons of functionality and fabrication, depressions on the surface of the carrier which are formed, for example, by openings of guides and channels for fluid or gaseous mediums or by any other reception-like depressions. In so far as the pressing-in forces for the interference fit are relatively high, it is possible for the rings to get upset and yield radially into the depressions. As a result, the rings get deformed particularly in the region of the depressions so that they assume a non-circular shape.
Due to the absence of radial support in the region of the depressions, the sheet metal of the wall sections with which the groove-shaped or opening-shaped depressions are covered, yields radially outwards when it is pressed in and radially inwards into the depressions when it is pressed on. Moreover, due to the stresses out of the interference fit, the components grip or undergo an equalizing displacement into the depressions. The contours of the channels change in such a way that non-circularities and other undesired shape deviations occur, so that piston running surfaces and sealing surfaces become non-circular and rolling contact surfaces inexact.
In such arrangements, therefore, an interference fit of the bushing-type components with the carriers is not used. This, however, also means that the non-circularities occurring in the bearing and on the sealing seats, as well as larger operational lashes are accepted. The components are then secured, for example, with the help of tabs on the corresponding seats as proposed, for example, in DE 10 2007 048 124 A1.
Thin-walled bushings are used, for example, as sealing bushings in transmissions comprising, inter-inserted shaft systems such as in converter transmissions or double clutch transmissions. These bushings seal oil-conveying structures, close fabrication-related openings or are used for a controlled supply of lubricating oil. Bushings of this type are frequently pressed into cylindrical bores of hollow shafts. In this case, a person skilled in the art is confronted with the problems described above. Deformations and faults occur in the region of depressions, for example on the sealed seats and can lead to losses due to leaks in these medium guides.
DE 42 38 147 A1 shows such medium guides in an automated transmission that are delimited by bearing rings of two rolling bearings and are formed on the surroundings of these. Each of the oil guides conveys pressure oil to one piston/cylinder unit of a hydraulically actuated clutch. Through the rolling bearings, a carrier of the hushing-type component, designated as a hollow cylindrical shaft section of a planetary transmission, is mounted for rotation in housing sections of hydraulic clutches of the automated transmission.
The first rolling bearing comprises an inner bearing ring and an outer bearing ring, both of which are configured as hollow cylindrical bushing-type components between which the rolling elements roll on rolling surfaces. The carrier for the inner bearing ring is a hollow cylindrical section of the housing of the first piston/cylinder unit of one of the hydraulically actuated clutches. The carrier for the outer bearing ring is a shaft section in whose inner cylindrical hole the bearing ring is seated and with which the hearing ring can rotate about an axis of rotation.
The second rolling bearing comprises an inner and an outer bearing ring with raceways for the roiling elements, both bearing rings being configured as bushing-type components. The inner bearing ring carrier which is rotatable about the axis of rotation is the cylindrical shaft section of the planetary drive. The carrier of the outer bearing ring is a housing of the second piston/cylinder unit of one of the hydraulically actuated clutches, the carrier being seated in the cylindrical bore of the housing.
The inner and outer bearing rings are likewise configured as sealing bushings and oil guiding elements and, in addition, they comprise sealing surfaces as well as the rolling surfaces for rolling elements. Pressure oil is guided via the channels in the hollow cylindrical shaft section at first to the outer bearing ring of the first rolling bearing and to the inner bearing ring of the second rolling bearing. The channels bear against the outer bearing ring of the first rolling bearing and against the inner bearing ring of the second rolling bearing.
The outer bearing ring of the first rolling bearing comprises a radial through-aperture that communicates for oil transfer with one of the channels of a first oil guide. Through this aperture, oil can flow out of the channel into the interior of the first bearing to the inner bearing ring. The inner bearing ring likewise comprises a radial through-aperture that communicates with a further channel of the first oil guide for oil transfer in direction of the first piston/cylinder unit.
The inner bearing ring of the second rolling bearing closes the channel of the first oil guide, so that no oil can flow out of the first oil guide into the second rolling bearing. However, the inner bearing ring of the second rolling bearing comprises a radial through-aperture that communicates for oil transfer with a channel of a second oil guide. Further, the outer bearing ring of the second rolling bearing comprises a radial through-aperture that communicates for oil transfer with a further channel of the second oil guide which leads to the second piston/cylinder unit.
Both the first rolling bearing and the second rolling bearing are sealed laterally from the surroundings, so that hardly any pressure oil can escape from the rolling bearings to the surroundings. For this purpose, the outer bearing ring of each of the rolling bearings comprises sealing surfaces against each of which a sealing ring bears.